In recent years, molded thermoplastic resin articles are used in a wide range of areas, including the parts of household electric appliances, OA apparatuses, motor vehicles, etc. However, the thermoplastic resins constituting the molded thermoplastic resin articles are mostly electrically insulating, and have a problem that the malfunctions of controllers are caused due to the electrostatic charges generated in the various apparatuses equipped with precise electric and electronic control devices. As methods for solving the problem caused by these electrostatic charges, methods of mixing an amine-based antistatic agent with a thermoplastic resin are disclosed. Further, as methods for keeping a thermoplastic resin continuously antistatic, methods of mixing a polyamide elastomer such as a polyether-ester amide are disclosed. However, the thermoplastic resins made to have antistatic performance by these methods are not sufficiently antistatic, depending on applications, and do not exhibit the required performance satisfactorily as the case may be.
As further other methods for making a thermoplastic resin antistatic, methods of mixing carbon black as a conductive filler with a thermoplastic resin are known. However, a thermoplastic resin containing carbon black has a problem that the color of the molded thermoplastic resin article is limited to black and a problem that, since it is necessary to mix a relatively large amount of carbon black for obtaining a stable resistance value in the electrostatically charged region, the mechanical properties of the molded thermoplastic resin article decline.
As still further other methods for making a thermoplastic resin antistatic, proposed are methods of mixing carbon fibers, metal fibers or metal powder as a conductive filler with a thermoplastic resin. However, the molded thermoplastic resin articles obtained by these methods have such problems that the appearance of the products is poor and that the mechanical properties decline.
Methods recently proposed to solve the problems of the thermoplastic resins made antistatic by these conventional methods include a method of mixing an ionic salt obtained from nonpolymeric nitrogen onium cation and weakly coordinating fluoroorganic anion with a thermoplastic resin (JP 2003-511505 T2), a method of mixing a perfluoroalkylsulfonate (JP 2003-507510 T2), and a method of combining an onium salt of a cyclic amidine or pyridine with a polymeric compound (JP 10-265673 A), etc. However, these proposals do not satisfactorily provide the high antistatic property required especially in the area of electronic and electric apparatus parts, etc. Further, there is no particularly disclosed application to a styrene-based thermoplastic resin, and the applicability to the styrene-based resin is unknown.